1. Field of the Invention
Clay tile pipe joint seals fabricated from organic resins.
2. Description of the Prior Art
Clay tile pipes customarily are formed in a bell and spigot configuration. As a consequence of the high temperature firing to which clay tile pipes are exposed during fabrication, they are customarily non-uniform with respect to the outer diameter of the spigot end and the inner diameter of the bell end of each pipe unit. Concentricity is difficult to maintain. The clay tile pipe industry has accepted non-uniform cross-sectional profiles of the bell and spigot ends of the clay tile pipe and has developed joint seals which are resilient and which accommodate the irregularities. The very early prior art employed materials which were stuffed into the bell after the bell and spigot had been carefully aligned in position for ultimate use. Such stuffing materials included hemp, oakum, and other fibrous materials and other tacky materials such as asphalt. The stuffing was accomplished by tamping with suitable manual tools. Subsequently the clay tile pipe industry developed factory applied joint seals for the bell interior and for the spigot exterior which can be engaged to accommodate the spigot end of one clay tile pipe with the bell end of an engaged clay tile pipe.
Increased cost of unsaturated polyester resin materials for use in joint seals of clay tile pipes has caused the industry to re-evaluate earlier pipe joint sealing techniques in attempts to minimize overall installation costs. There is a clear-cut need for an improved clay tile pipe joint seal which will be as effective as the existing standard in the industry, that is, the unsaturated polyester resin joint seal, and yet which can offer significant cost savings over the existing unsaturated polyester resin construction.